[ARM] Add thread_notify infrastructure
Some machine classes need to allow VFP support to be built into the
kernel, but still allow the kernel to run even though VFP isn't
present. Unfortunately, the kernel hard-codes VFP instructions
into the thread switch, which prevents this being run-time selectable.
Solve this by introducing a notifier which things such as VFP can
hook into to be informed of events which affect the VFP subsystem
(eg, creation and destruction of threads, switches between threads.)
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index ab8e600..86c9252 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -20,6 +20,7 @@
#include <asm/glue.h>
#include <asm/vfpmacros.h>
#include <asm/arch/entry-macro.S>
+#include <asm/thread_notify.h>
#include "entry-header.S"
@@ -560,10 +561,8 @@
add ip, r1, #TI_CPU_SAVE
ldr r3, [r2, #TI_TP_VALUE]
stmia ip!, {r4 - sl, fp, sp, lr} @ Store most regs on stack
-#ifndef CONFIG_MMU
- add r2, r2, #TI_CPU_DOMAIN
-#else
- ldr r6, [r2, #TI_CPU_DOMAIN]!
+#ifdef CONFIG_MMU
+ ldr r6, [r2, #TI_CPU_DOMAIN]
#endif
#if __LINUX_ARM_ARCH__ >= 6
#ifdef CONFIG_CPU_32v6K
@@ -585,21 +584,20 @@
#ifdef CONFIG_MMU
mcr p15, 0, r6, c3, c0, 0 @ Set domain register
#endif
-#ifdef CONFIG_VFP
- @ Always disable VFP so we can lazily save/restore the old
- @ state. This occurs in the context of the previous thread.
- VFPFMRX r4, FPEXC
- bic r4, r4, #FPEXC_ENABLE
- VFPFMXR FPEXC, r4
-#endif
#if defined(CONFIG_IWMMXT)
bl iwmmxt_task_switch
#elif defined(CONFIG_CPU_XSCALE)
- add r4, r2, #40 @ cpu_context_save->extra
+ add r4, r2, #TI_CPU_DOMAIN + 40 @ cpu_context_save->extra
ldmib r4, {r4, r5}
mar acc0, r4, r5
#endif
- ldmib r2, {r4 - sl, fp, sp, pc} @ Load all regs saved previously
+ mov r5, r0
+ add r4, r2, #TI_CPU_SAVE
+ ldr r0, =thread_notify_head
+ mov r1, #THREAD_NOTIFY_SWITCH
+ bl atomic_notifier_call_chain
+ mov r0, r5
+ ldmia r4, {r4 - sl, fp, sp, pc} @ Load all regs saved previously
__INIT